Paper documents via the electrostatic control of particles

Paper documents continue to be a user-friendly medium for disseminating and archiving information. Although the vast majority of documents are printed with offset technology, a growing percentage (∼30% in US) is produced by digital copiers and printers based on the electrostatic control of charged particles. Electrophotography represents the dominant electrostatic marking technology. However, alternative marking concepts based on different types of electrostatic imaging physics have been proposed in recent years to improve the cost and image quality of electrostatically produced paper documents. To provide a framework for discussion, the marking concepts are grouped into one of three system approaches. The system approaches are (1) indirect marking by developing a latent electrostatic image with charged particles that are subsequently transferred to paper (exemplified by electrophotography), (2) direct marking of charged particles onto an intermediate or paper, and (3) rewritable electronic paper displays enabled by electrostatically controlling the rotation or translation of encapsulated charged particles coated on a paper substrate. The different system approaches are illustrated by examples of current and proposed concepts for printers and displays.